Gas turbine single plant modifying method, a catalyst re-using method and a re-produced catalyst
Patent 7316988 Issued on January 8, 2008. Estimated Expiration Date: 
April 3, 2023. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
April 3, 2023. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3260505 Process for regenerating an antimony containing oxide catalyst Denitration catalyst and denitrating method Method for recovering denitrating catalyst for ammonia catalytic reduction Waste heat recovery system Exhaust gas-purifying catalyst and process for purifying exhaust gases Catalyst and method for denitrization of nitrogen oxides Process for the production of mixed oxide powders for catalysts for the removal of nitrogen oxides Nitrogen oxide removal control apparatus Gas turbine for the combustion of reformed fuel gas InventorsAssigneeApplicationNo. 10405618 filed on 04/03/2003US Classes:502/312, Vanadium containing502/20, REGENERATING OR REHABILITATING CATALYST OR SORBENT502/309, Titanium containing502/350, Of titanium502/353, Of Group V (i.e., V, Nb, Ta, As, Sb or Bi)502/22, Treating with a liquid or treating in a liquid phase, including dissolved or suspended416/179, ROTOR HAVING FLOW CONFINING OR DEFLECTING WEB, SHROUD OR CONTINUOUS PASSAGE423/239.1, Utilizing solid sorbent, catalyst, or reactant502/26, Ammonia or derivative thereof502/74, And Group VIII (Iron Group or Platinum Group) containing60/39.465, Gaseous fuel at standard temperature and pressure148/404, Directionally solidified502/27, Using acid502/220Molybdenum containingExaminersPrimary: Nguyen, Cam N.Attorney, Agent or FirmForeign Patent References
International ClassesB01J 23/00B01J 23/24 B01J 21/00 DescriptionBACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying a gas turbine single plant into a combined cycle plant comprising a combination of the gas turbine, a waste heat recovery boiler and a steam turbine and a method for re-using a used hightemperature denitration catalyst of the gas turbine single plant as an intermediate temperature denitration catalyst of other modified, existing or new plants, and also relates to a re-produced catalyst. 2. Description of the Prior Art Recently, in order to cope with an urgent demand for electric power, there are often constructed gas turbine single plants that are excellent in operability and constructible with less investment cost and over a shorter period. However, the gasturbine single plant is less excellent in long term plant efficiency, and hence it is effective that a gas turbine single plant is first constructed to be modified in the future by re-powering work into a combined cycle plant that is excellent in plantefficiency. (See Patent Document 1 below, for example.) On the other hand, in denitration equipment that is installed for denitration of the exhaust gas in a power plant or the like, there is used a catalyst that contains TiO2 (titanium oxide) as a main component and includes at least one ofWO3 (tungsten oxide) and MoO3 (molybdenum oxide) and further includes V2O.sub.5 (vanadium oxide). In the gas turbine single plant, as the temperature of the exhaust gas to be denitrified is as high as 450 to 600° C., a high temperature denitration catalyst is used. In the high temperature denitration catalyst, V2O.sub.5 that isvulnerable at the high temperature is used only in a minute amount or no V2O.sub.5 is included. (See Patent Document 2 below, for example.) That is, the denitration catalyst containing the minute amount or none of V2O.sub.5 component is a catalyst that is optimized for high temperature. Hence, if the gas turbine single plant is once re-powered into a combined cycle plant asmentioned above, this high temperature denitration catalyst cannot be used for the combined cycle plant in which the temperature of the exhaust gas to be denitrified is an intermediate temperature of 200 to 450° C. For the reason as explained above, when the gas turbine single plant is to be re-powered into the combined cycle plant, the high temperature denitration catalyst that has been used in the gas turbine single plant is wasted and an intermediatetemperature denitration catalyst must be newly adopted for the combined cycle plant. This invites an increase in the investment cost of the plant. Patent Document 1 Japanese laid-open patent application 1996-260912 (Paragraphs 0004, 0005 and 0009 to 0018) Patent Document 2 Japanese laid-open patent application 1994-079139 (Paragraphs 0013 to 0018) SUMMARY OF THE INVENTION In view of the problem in the prior art, it is an object of the present invention, when a gas turbine single plant is to be modified into a combined cycle plant, to provide a method for economically realizing the combined cycle plant by which ahigh temperature denitration catalyst that has been used in the gas turbine single plant is re-produced as an intermediate temperature denitration catalyst to be re-used as a denitration catalyst of the combined cycle plant. It is also an object of thepresent invention to provide a method for re-using a used high temperature denitration catalyst as well as to provide a re-produced catalyst. In order to achieve the above mentioned object, the present invention provides a method for modifying a gas turbine single plant into a combined cycle plant by which, in modifying the gas turbine single plant into a combined cycle plant, a usedhigh temperature denitration catalyst is reproduced as an intermediate temperature denitration catalyst, and this re-produced intermediate temperature denitration catalyst is re-used as a denitration catalyst of the combined cycle plant after beingmodified. According to this modifying method, the used high temperature denitration catalyst of the gas turbine single plant is re-produced as the intermediate temperature denitration catalyst to be used for the combined cycle plant. Thereby, theequipment cost required for the re-powering of the plant can be largely reduced. Thus, according to the modifying method of the present invention, the used high temperature denitration catalyst is re-used, the waste cost thereof is saved and thereby a burden on the environment caused by the waste can be alleviated. Also, the present invention provides a method for re-using a used high temperature denitration catalyst by which the used high temperature denitration catalyst of a gas turbine single plant is re-produced as an intermediate temperaturedenitration catalyst, and this re-produced intermediate temperature denitration catalyst is re-used as an intermediate temperature denitration catalyst of other modified, existing or new plants. According to this re-using method of the present invention, in re-powering the gas turbine single plant, the used high temperature denitration catalyst can be effectively re-used as an intermediate temperature denitration catalyst and thereby are-selling business of the catalyst as an intermediate temperature denitration catalyst of modified, existing or new plants other than the mentioned gas turbine single plant can be appropriately realized corresponding to a required amount of thecatalyst, a geographical position of the plant or the like. In a representative high temperature denitration catalyst used in the gas turbine single plant as the object of the present invention, TiO2 is included as a main component and at least one of WO3 and MoO3 is also included. Also,the composition may include V2O.sub.5 of 0.5 wt(weight) % or less, preferably 0.2 wt % or less, or may include none of V2O.sub.5. Especially if the used high temperature denitration catalyst is of the above mentioned composition, the quantity of the catalyst available for re-use is large and thus the modifying or re-using method of the present invention is extremelyeffective. Also, with respect to the above mentioned modifying or re-using method, the present invention provides a modifying or re-using method in which the intermediate temperature denitration catalyst is re-produced by including V2O.sub.5 componentof 0.5 wt % or more, preferably 1.0 wt % or more, in the used high temperature denitration catalyst, as well as providing a re-produced catalyst that is re-produced with the same composition included in the used high temperature denitration catalyst. Further, with respect to the above mentioned modifying or re-using method, the present invention provides a modifying and re-using method in which, where the high temperature denitration catalyst to be re-used is a catalyst that is optimized soas to be used in the temperature range up to maximum 450 to 600° C., the intermediate temperature denitration catalyst is re-produced by including a V (vanadium) component in the used high temperature denitration catalyst and is optimized so asto be used in the temperature range of 200 to 450° C., as well as providing a re-produced catalyst that is optimized for the same temperature range. Also, with respect to the above mentioned modifying or re-using method, the present invention provides a modifying or re-using method in which the inclusion treatment of the V component is carried out by immersion into a V-containing watersolution and drying and/or burning as well as providing a re-produced catalyst that is re-produced by the same treatment. According to the present invention, which has been made based on the expertise obtained by extensive studies on the temperature characteristics of the TiO2 group denitration catalyst and on the re-producing technology of the denitrationcatalyst, when a gas turbine single plant is to be modified to be re-powered into a combined cycle plant, a modifying or re-using method and a re-produced catalyst by which the equipment cost can be extremely reduced, as well as the influence given onthe environment is largely alleviated can be provided. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a combined cycle plant made by modification of a gas turbine single plant of FIG. 4. FIG. 2 is an explanatory view showing one example of a modified construction of the combined cycle plant of FIG. 1. FIG. 3 is an explanatory view showing another example of a modified construction of the combined cycle plant of FIG. 1. FIG. 4 is an explanatory view showing a construction of a gas turbine single plant in the prior art before it is modified into a combined cycle plant by applying the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below more concretely based on embodiments. FIG. 4 shows a gas turbine single plant in the prior art before it is modified into a combined cycle plant by applying the present invention. In FIG. 4, numeral 1 designates gas turbine equipment, numeral 2 designates a compressor and numeral 3 designates a gas turbine. The construction is made such that exhaust gas of the gas turbine 3 flows through a duct 4 to be led intodenitration equipment 6 for denitration treatment therein and then further flows through a duct 5 to be emitted into the air from a stack 7. The temperature of the exhaust gas coming from the gas turbine 3 to be led into the denitration equipment 6 is as high as 450 to 600° C. Thus, in the denitration equipment 6 that effects the denitration treatment, a high temperaturedenitration catalyst is used so as to withstand such a high temperature for effecting the denitration reaction. While the denitration catalyst contains TiO2 as a main component and an active component, such as WO3 or MoO3, as the gas to be treated is of the high temperature as mentioned above, inclusion of a V component in the catalyst isvery small or even zero such that V2O.sub.5, which is thermally vulnerable, is 0.5 wt % or less, preferably 0.2 wt % or less, or no V2O.sub.5 is included. In the denitration equipment 6 using the denitration catalyst as mentioned above, the exhaust gas to be treated for denitration is first injected with NH3 (ammonia) so as to be made to contact with the catalyst, and by the reactions of4NO 4NH3 O2→4N.sub.2 6H2O, NO NO2 2NH3→2N2 3H2O, NO and NO2 are decomposed into an innoxious nitrogen and water. FIG. 1 shows a combined cycle plant modified by applying the present invention. In FIG. 1, numeral 9 designates an exhaust gas boiler that uses the exhaust gas of the gas turbine equipment 1 as a heat source. Numeral 10 designates a steamturbine that is operated by being supplied with steam generated at the exhaust gas boiler 9. As the result of heat recovery at the exhaust gas boiler 9, the temperature of the exhaust gas coming out of the exhaust gas boiler 9 is reduced to anintermediate temperature of 450 to 200° C. This intermediate temperature exhaust gas is applied with the denitration treatment at the denitration equipment 8 and is then emitted into the air from the stack 7. In the denitration equipment 8 that treats this intermediate temperatureexhaust gas of 450 to 200° C., the intermediate temperature denitration catalyst obtained by the present invention is used. That is, the intermediate temperature denitration catalyst to be used in the denitration equipment 8 is re-produced from the high temperature denitration catalyst that has been used in the denitration equipment 6 of the gas turbine single plantshown in FIG. 4. As mentioned above, the high temperature denitration catalyst used in the denitration equipment 6 of FIG. 4 contains TiO2 as a main component and an active component of WO3 or MoO3 or the like, but inclusion of the V component thatis thermally vulnerable is very small or even zero. In order to produce the intermediate temperature denitration catalyst for the denitration equipment 8 from the used high temperature denitration catalyst of the denitration equipment 6, the used high temperature denitration catalyst is treated soas to contain V2O.sub.5 of 0.5 wt % or more, preferably 1.0 wt % or more. For treating the TiO2.WO.sub.3 group high temperature denitration catalyst so as to contain V2O.sub.5, the catalyst is first immersed in an oxalic acid solution of V2O.sub.5 and is then dried and/or burned. If drying only isapplied, the catalyst is changed to a burned state by the exhaust gas in actual operation. One example of the procedures to treat the TiO2.WO.sub.3 group high temperature denitration catalyst so as to contain V2O.sub.5 is shown next: (1) Measurement of Water Content of the Catalyst The catalyst is immersed into water, the weight of the catalyst before and after immersion being measured, and the water content is decided by the following equation: Water content a (liter/kg)=(W2-W1)/W1(liter/kg) Here, W1 is weight of the catalyst before immersion (kg) and W2 is weight of the catalyst after immersion (kg). (2) Decision of V2O.sub.5 Concentration of the Immersion Liquid V2O.sub.5 concentration of the immersion liquid is decided by the following equation: V2O.sub.5 concentration X(kg/liter)=B×0.01/a Here, B is the desired V2O.sub.5 concentration in the catalyst and a is the water content (liter/kg). (3) Adjustment of the Immersion Liquid Oxalic acid (H2C.sub.2O.sub.4) of 2.5 Xkg is dissolved in warm water of about 0.9 liter. V2O.sub.5 powder Xkg is gradually added into this solution to be dissolved therein and then water is added so that a solution for immersion of 1liter is made. The used high temperature denitration catalyst is immersed into this immersion solution for about 1 minute. Then, this catalyst is dried and burned for 3 hours at 550° C. In the above, while the present invention has been concretely described based on one embodiment, it is needless to mention that the invention is not limited to this embodiment but may be added to with various changes and modifications within thescope of the present invention as defined by the appended claims. For example, the high temperature denitration catalyst to be re-used is not necessarily a TiO2.WO.sub.3 group catalyst. Also, while the composition ratio of the high temperature denitration catalyst has been taken from a basic framework that TiO2 is 60 to 80 wt %, WO3 (MoO3) is 5 to 25 wt % and V2O.sub.5 is 0 to 10 wt %, wherein MoO3 isthe alternative for WO3, the composition ratio may be optimized according to the fuel for combustion, the temperature of the gas to be treated, etc. Moreover, the procedure of treatment to give V component to the catalyst is not limited to the use of the oxalic acid solution but, for example, citric acid water solution, methylamine water solution of ammonium metavanadic acid, sulfamic acidwater solution, etc. may be used as a wash medium. In the above described embodiment as shown in FIG. 1, while the example of the construction of the combined cycle plant modified so as to have the denitration equipment 8 downstream of the exhaust gas boiler 9 has been described, if, in the gasturbine single plant, such a construction arrangement is considered beforehand that a space is left upstream of the denitration equipment 8 so that the exhaust gas boiler 8 may be added upstream of the denitration equipment 8 in the future when the gasturbine single plant is to be modified into a combined cycle plant, then the modification to the combined cycle plant can be done most easily and with less modification cost. In this case, as no exhaust gas boiler is to be provided downstream of thedenitration equipment and no waste heat recovery is to be carried out in the low temperature range, there is left room for further enhancing the efficiency in the plant operation. Also, the construction shown in FIG. 2 in which the denitration equipment 8 is interposed between an exhaust gas boiler 9-1 and an exhaust gas boiler 9-2 is made such that, in the gas turbine single plant, spaces are left beforehand upstream anddownstream of the denitration equipment 8 and the two exhaust gas boilers 9-1, 9-2 are added on both sides of the denitration equipment 8 later in the modification to the combined cycle plant. In this case, while the cost for modification to thecombined cycle plant becomes higher than the construction shown in FIG. 1, a larger waste heat recovery can be realized and a further enhanced efficiency can be expected in the plant operation. Further, the construction shown in FIG. 3 in which the denitration equipment 8 is assembled into the exhaust gas boiler 9 is made such that the denitration equipment 8 is structured beforehand so as to be assembled into the exhaust gas boiler andthe denitration equipment 8 is so assembled later in the modification to the combined cycle plant. In this case, while the equipment structure and the modification work become somewhat complicated, the high efficiency in the plant operation is expectedsimilarly to the construction shown in FIG. 2, the installation space is reduced and a compact sized plant can be realized. It is a matter of course that the present invention is applicable to the modification to the combined cycle plant having various construction arrangements other than those illustrated and described above. * * * * * |
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